diff -r 784c45b27326 src/internet-stack/tcp-socket-impl.cc
--- a/src/internet-stack/tcp-socket-impl.cc	Thu Nov 06 11:52:59 2008 -0800
+++ b/src/internet-stack/tcp-socket-impl.cc	Thu Nov 06 15:46:32 2008 -0500
@@ -456,6 +456,12 @@
 TcpSocketImpl::Listen (void)
 {
   NS_LOG_FUNCTION (this);
+  //linux quits EINVAL if we're not closed, so match what they do
+  if (m_state != CLOSED)
+    {
+      m_errno = ERROR_INVAL;
+      return -1;
+    }
   Actions_t action = ProcessEvent (APP_LISTEN);
   ProcessAction (action);
   return 0;